Publications (6)34.43 Total impact
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Article: Conservation. Reconsidering the consequences of selective fisheries.
Science 03/2012; 335(6072):1045-7. · 31.20 Impact Factor -
Article: Additions and Corrections - Stereochemistry of Metal Anion Substitutions on Carbon
02/2004; -
Article: Starburst dendrimers. III. The importance of branch junction symmetry in the development of topological shell molecules
04/2002; -
Article: Starburst dendrimers. 4. Covalently fixed unimolecular assemblages reiminiscent of spheroidal micelles
04/2002; -
Article: Multichannel EEG power reflects information-processing and attentional demands during visual orienting
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ABSTRACT: The effects of stimulus complexity and instructions on the EEG orienting response were studied. Temporal and topographical EEG spectral changes from 01, 02, P3, P4, F3, F4, Fz, and Cz were recorded during orienting to, and appraisal of, visual stimuli of varying complexity. Only half the sample of 40 subjects was instructed to attend to the stimuli. Higher stimulus complexity reduced EEG power within beta, mid and high alpha rhythms, whereas the low alpha range was most sensitive to the interaction between stimulus complexity and instructions. Temporal changes in power suggested that the effect of stimulus complexity may be due to late appraisal rather than to early orienting. No single EEG index differentiated between groups. However, when factor scores of relative alpha, beta, and theta power were subjected to discriminant analysis, clear differences appeared between groups. Active attention during visual orienting was associated with a blockade and theta enhancement in posterior leeds, which might reflect two different mechanisms of orienting. Finally, EEG power changes during stimulus exposure predicted performance in a subsequent recognition task. it is argued that the analysis of short-lasting EEG power changes can offer valuable information about the mechanisms of visual orienting, and that a multivariate approach is required in EEG research on attention.Journal of Psychophysiology. 01/1995; 9(1):32-44. -
Article: A psychophysiological inquiry into the nature of the Sokolovian orienting response comparator model - Skin-conductance and EEG data
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ABSTRACT: The mechanisms which trigger the orienting response (OR) are still the subject of lively debate. Sokolov (1990) proposes the development of a multidimensional model of the physical parameters of stimulation. Recent OR research has shown that the skin conductance OR (SCOR) is related to task demands and controlled processing, although this is not so clear for central physiological indexes of orienting. Seventy-three subjects performed visual discriminations of stimuli within a warning-stimulus paradigm. The physical complexity of stimuli and their task relevance were manipulated within subjects, while the nonspecific effects of workload were controlled with a group factor. SCORs were measured concurrently with 1-s epochs of EEG alpha and theta power from Fz, Ct, Pt, and Oz. Neither index was reliably affected by the physical complexity of stimulation alone. However, both higher task relevance and higher workload significantly increased the magnitude of EEGORs and SCORs. Task averages of central and autonomic activity showed an overall pattern of covariation, but a second-by-second breakdown of EEG spectra suggests that the SCOR may be an aggregate of the activation of diverse brain mechanisms responsible for physiological orienting. The results are consistent with a model of orienting as a continuous dimension of resource allocation to anticipated and current task demands, rather than with the abrupt dichotomy between voluntary and involuntary orienting. Implications for the classical OR Sokolovian model are discussed.Biological Psychology 01/1995; 41(2):147-166. · 3.22 Impact Factor
